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I am trying to find an optimal method for managing exterior wood defects. The problem relates to the natural expansion and contraction of wood and the seeming inability of 'filling materials' to fix cracks and joints.
To seal and hide scarf joints in a DRY redwood deck rail prior to painting I have used water-based wood fillers, polyester resin fillers, acrylic-latex caulking, and even WoodEpox®. They have all failed. As soon as the wood heats up a little the filler gets pushed out of the gap and loosens the paint. Using an oil-based primer helped [the latex-based one was a disaster] but it didn't SOLVE the problem.
On my son's house we have a similar kind of problem but it's where the butt joints of the redwood siding come together. This was an addition to an OLD house and, unfortunately, lots of the butt joints line up vertically. Polyester resin and/or acrylic latex caulk were used. Almost all of the paint is failing along those joints and the paint's only 3 years old. I tried to attach photos of the problem but can't make a file that small. 19K? Come on. I can send photo if you want.
What do you professionals recommend for this problem? How can I fill checks in the railing or fascia and gaps in the siding without losing the covering paint from expansion and contraction? There's GOT to be a way to get a nice, smooth, STABLE finish.
Thanks, folks.

11-28-2011, 04:03 PM

Sombreuil_mongrel

Re: Wood Siding Joint Management

Try an epoxy system, like advanced restoration technology's flex-tech.
[url]http://www.advancedrepair.com/architectural_epoxy/ART_system_faq.htm[/url]
We use about 5 tubes of this stuff per year, and it is really a user-friendly product.
Casey

11-28-2011, 04:27 PM

RobertL39

Re: Wood Siding Joint Management

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Thanks. I've seen that but haven't used it. I've used the WoodEpox, which is a 2-component epoxy mixture. I've also used FillIt® epoxy from The Rot Doctor. The WoodEpox is easy to use but ends up pretty brittle. FillIt is more of a glue and hard to work with. Is the flex-tech easier to work with, or super-sticky like the FillIt? Do you have any [I]long-term[/I] results in either siding butt joints or checks in fascia or railing? Have you used either of the other two? If so, how do they compare?
Thanks a ton! I'll get there some day. Now, if I only knew where that was...

11-28-2011, 06:09 PM

jkirk

Re: Wood Siding Joint Management

for wood siding, the first i dont use is latex caulking.. though it may say its for exterior use.. it isn't its for interior dry conditions. ive seen it used countless times by homeowners and by wnana be contractors and the stuff doesnt keep water out.. for exterior use you need to use a polybutyl caulking or a polyeurathane based caulking. these types of caulking are proven and actually work

as for joints in the siding, every install i do for wood lap style siding or fiber cement siding. behind every butt joint i insall a 5" wide peice of aluminum or house wrap that acts as a flashing.. this goes half way on the joint and laps down over the lower peice by about 3/4" so it does its job and isnt visable when the next row goes on. when making scarf joints with wood siding, unlike popular belief a 45 deg scarf doesnt perform as well, by making such a steep angle joint the wood becomes more susceptible to shrinking which lets water get in, i use a 30 degree angle which still looks just as good but wont shrink as much. in conjunction i use the joint flashing technique and run a very thin bead of clear caulking in the joint then wipe off any excess once the next peice is in place

i havent used epoxy to deal with defects but it does work, i typically do a visual inspection of every piece of wood siding before it goes on the side wall, any pieces with defects get set aside to be used for shorter pieces and the defect cut out.. if the siding is already on the wall and there are defects that need to be dealt with . by all means use the epoxy

11-28-2011, 06:42 PM

RobertL39

Re: Wood Siding Joint Management

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Thanks! How ARE things up there in the cold Northeast? You must have some considerable experience with this kind of thing, given the nature of your climate up there.
Polyurethane caulk dries rock hard as best I can tell. I assume its adhesion is good, but don't know. I've never used polybutyl. Does it have some give to it as well as excellent adhesion? Are either of them semi-easy to work with, as in using a putty knife to spread and smooth? Sandable? Would you use one of those to deal with deep checks [1/4" wide by 18" long, for example] in fascia boards? Have you tried the new paintable GE silicone? Goes on well and takes paint just fine.
Many thanks for your thoughts. Keep the fire going!

11-28-2011, 07:15 PM

jkirk

Re: Wood Siding Joint Management

my climate is pretty harsh at times, we can have 30 degree celcius days in the summer and -25 in the winter. im directly on the coast so we experience all kinds of weather from hurricane force winds, terrential rain, freezing rain and the odd blizzard like situation so our prep for siding is pretty extreme. have to keep the water out yet allow the siding to properly dry so it doesnt rot. a week ago we were hit with almost 10" of snow and today it was nearly tshirt weather while working outside

polyeurathane caulking is more designed for commercial use, im going through it like mad right now on a 86 unit high end apartment building im currently siding with fibre cement. were using dynomic which is sold strictly for industrial and commercial use

as for polybutyl, flex 9000, flextra, quad are all this type of caulking and work wonders, as long as the substrate is clean and dry they adhere perfectly, all of them can stretch up to 4x the volume they have when they come out of the tube, i use flex 9000 for setting windows and doors along with back caulking all my wood trim for siding and for face caulking siding and aluminum cladding

11-28-2011, 11:23 PM

ordjen

Re: Wood Siding Joint Management

Two elastomeric urethane caulks I have used and been very satisfied with are Vulkem 116 and Sonneborne NP-1. They hold tenaciously, are elastomeric to stretch with the seasonal movement, hold paint well and ,because of their heavy viscosity, can close a gap which no acrylic caulk could begin to do. Also, urethanes actually need moisture to cure. The surface should be dry at the moment of application, but because they are not water soluble, they won't wash off it it starts raining a couple seconds after application. Acrylic caulks would sit there for hours, vulnerable to rain, in cool damp weather.

11-29-2011, 01:29 PM

Sombreuil_mongrel

Re: Wood Siding Joint Management

Yes the Abatron putty epoxy is rather brittle. We always cut the joints so the woodepox is not bridging two different components or the joint (esp a 90* one) will cause it to crack. But it's great for work that needs a like-new smooth or moulded surface.
The ART Flextech is a gel. It remains quite flexible; the downside is that it's hella hard to feather out or shape (compared to woodepox). I have been using the Abatron stuff since 1986, and only in the last 5 or so years begun to use Flextech. The other reason for my recommendation is that the first step of the ART system (as with Abatron) is the penetrating/sealer step, which makes it possible for the gel to deeply bond with the wood fibers.
Since you were asking about siding butt joints, I'm hearing "end grain" and any caulk job on end grain will only last until that wood gets wet. No sealant can stick once the wood's damp. The penetrating epoxy makes this a non-issue, and the sealant will continue to seal.
The lexel/geocell type flexible, paintable sealants are also good partners after the end grain has been sealed, but they are completely unworkable after drying, and the closest you can come to giving them any kind of shape is to work them with a thinner soaked rag, etc. And any subsequent fillers added are in real jeopardy of popping loose. Up high and out of sight they are invaluable.
Casey

11-29-2011, 04:42 PM

RobertL39

Re: Wood Siding Joint Management

Thanks again, Casey. Great information. Yes, it's end grain.
I'm a little confused about using Geocell/Lexel paintable sealants AFTER sealing the end grain? Why seal over sealed grain? And not using GEs paintable silicone called Groov? Seems like that should stick and stay even if the wood gets wet.
There are SO many sealants it's hard to keep them straight! Thanks for trying to help ME keep them straight.

11-29-2011, 04:49 PM

RobertL39

Re: Wood Siding Joint Management

Since you mentioned putting xxx back in Christmas:

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